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Although excellent milestones of III-nitrides in optoelectronic devices have been achieved, the focus on the optimization of their geometrical structure for multiple applications is very rare. To address this issue, we exclusively designed a prototype device to enhance the photoconversion efficiency and gas interaction capabilities of GaN nanorods (NRs) grown on a V-grooved Si(100) substrate with Si(111) facets for photodetector and gas sensor applications. Photoluminescence studies have demonstrated an increased surface-to-volume ratio and light trapping for GaN NRs grown on V-grooved Si(111). GaN NRs on V-grooved Si(100) with Si(111) facets exhibited high photodetection performance in terms of photoresponsivity (217 mA/cm2), detectivity (3 × 1013 Jones), and external quantum efficiency (2.73 × 105%) compared to GaN NRs grown on plain Si(111). Owing to the robust interconnection between NRs and a high surface-to-volume ratio, the GaN NRs grown on V-grooved Si(100) with Si(111) facets probed for NO2 detection with the assistance of photonic energy. The photo-assisted sensing makes it possible to detect NO2 gas at the ppb level at room temperature, resulting in significant power reduction. The device showed high selectivity to NO2 against other target gases, such as NO, H2S, H2, NH3, and CO. The device showed excellent long-term stability at room temperature; the humidity effect on the device performance was also examined. The excellent device performance was due to the following: (i) benefited from the V-grooved Si structure, GaN NRs significantly trapped the incident light, which promoted high photocurrent conversion efficiency and (ii) GaN NRs grown on V-grooved Si(100) with Si(111) facets increased the surface-to-volume ratio and thus improved the gas interaction with a better diffusion ratio and high light trapping, which resulted in increased response/recovery times. These results represent an important forward step in prototype devices for multiple applications in materials research.

Significant efforts are being put into the development of efficient micrometer-scale light emitting diodes (LEDs) for future display technologies due to their marked benefits over existing displays. To date, however, the efficiency of microLED devices remains significantly lower than that of conventional broad-area devices. The deterioration in device performance with smaller device size has been linked to the plasma damage induced on mesa sidewalls during device fabrication. Here, we studied bottom-up red-emitting nanowire LEDs with different Mg doping levels in the p-GaN layer. The resulting sub-micron LED devices show a distinct improvement in efficiency with increasing Mg dopant incorporation. Through optimization of the doping, we measured an external quantum efficiency of ∼8.3% and a wall-plug efficiency of ∼4.6%, at a current density of ∼1 A/cm2, for a red-emitting sub-micrometer scale LED operating at >630 nm. This study highlights the importance of p-doping in microLEDs for attaining high efficiency performance in nanostructure-based devices.

Herein, we demonstrate the ultraviolet (UV) light activated high-performance room-temperature NO gas sensor based on nitrogen-doped graphene quantum dots (NGQDs)-decorated TiO2 hybrid structure. Ti...

Nitrogen dioxide (NO

We present the influence of vacuum annealing on RF magnetron-sputtered TiO2−x thin films grown at various oxygen partial pressures ($$p_{{{\text{O}}_{2} }}$$) of 2.0%, 4.0% and 6.0% to enhance the ultra-violet (UV) photodetector performance. Apart from the film deposited at 2.0% of $$p_{{{\text{O}}_{2} }}$$, all the as-grown TiO2−x films show an amorphous nature, whereas thermally annealed TiO2−x films at 400 °C show the rutile phase. As revealed by the linear current–voltage characteristics, the ohmic-contact behavior was observed between the TiO2−x layer and the electrode material. Benefiting from the above features, the photocurrent was significantly increased at 4.0% of $$p_{{{\text{O}}_{2} }}$$ due to the increase of oxygen vacancies and the suppression of electron–hole recombination. As a result, thermally annealed TiO2−x films are very useful for next-generation UV-photodetectors even at a lower power density of 1.72 mW/cm2. Therefore, the merits of the above findings present a promising strategy to enhance the UV photoresponse of thermally annealed TiO2−x films by optimizing the $$p_{{{\text{O}}_{2} }}$$ at 4.0%.

Although metal nanoparticles (NPs) have been widely reported, Au NPs functionalized reduced graphene oxide (rGO)/GaN nanorods (NRs) for multi-functional applications are rarely discussed. The rGO is a well known transparent electrode and has been considering an alternative electrode to ITO in the current optoelectronic community. In this work, Au NPs functionalized rGO (Au@rGO)/GaN NRs hybrid structure probed for photodetector and CO gas sensing applications. The hybrid structure was characterized by scanning electron microscopy, transmission electron microscope, current-voltage characteristics, photo conductivity, and gas sensor measurements. The Au@rGO/GaN NRs showed higher photoresponsivity (λ = 382 nm, 516 nm) compared to rGO/GaN NRs at room temperature. The rising and falling times of Au@rGO/GaN NRs are faster than that of rGO/GaN NRs. The hybrid structure Au@rGO/GaN NRs exhibited high CO gas response compared to rGO/GaN NRs at room temperature (∼38% to the 20 ppm). Au NPs played an important role in terms of electronic and chemical changes in the hybrid structure for improving both photodetectors the CO gas response. Such a multi-functional hybrid device is an interest of various room temperature applications.

In this work, we report on p-Phenylenediamine (PPD) functionalized reduced graphene oxide (rGO)/Si hybrid-structure designed for UV photodetector applications (PD). The hybrid-structure was characterized by using Fourier Transform-infrared spectroscopy, X-ray photoelectron spectroscopy to confirm the formation of nano-hybrid structure and the experimental results confirmed the covalent bond between rGO and PPD. The diode parameters such as barrier height, series resistance, and ideality factor were estimated for both PPD functionalized rGO (PrGO)/Si and rGO/Si heterostructure by using I-V characteristics. The time-resolved photocurrent spectroscopy used to examine the photoresponse properties of both PrGO/Si and rGO/Si samples with UV light (λ = 382 nm). The experimental results showed that PrGO/Si exhibited significant UV photoresponse than that of rGO/Si PD. The PrGO/Si heterostructure device exhibited photoresponsivity of 1.4 × 10−3 A/W, which is 15 times higher than rGO/Si. The high photoresponse was attributed to the synergistic effects originated from the charge transfer between PPD and rGO. The results proved that PrGO is a promising material for high response photodetector applications.

Considering the power consumption and safety risks in the presence of combustible gases, sensor operation at room temperature (RT∼28 °C) has drawn much interest in recent days. Different strategies have been found to meet the effective sensor performance at RT. Here, we report a riveting combination of DNA‒CTMA/GaN (DGaN) hybrid structure for high-sensitive NO2 gas sensor at RT. The surface modifications are caused by the functional groups of DNA‒CTMA interactions with GaN. The XPS studies reveal that the native oxides of GaN surface are binding with the functional groups of DNA‒CTMA. The DGaN hybrid structure display higher response to various concentrations (100–10 ppm) of NO2 compared to the pristine GaN film. The effect of UV illumination on NO2 gas sensing performance of DGaN is also manifested, and the response of the sensor is enhanced under UV illumination in comparison with those of dark condition. From our observations, the amine groups and the negatively charged hydroxyl groups in DNA‒CTMA helps for the higher response of gas sensor by the hybrid structure which makes them a good candidate for high-response NO2 gas sensors at RT.

Even though lanthanide ion (Ln3+)-doped DNA nanostructures have been utilized in various applications, they are rarely employed for photovoltage generating devices because of difficulties in designing DNA-based devices that generate voltages under light illumination. Here, we constructed DNA lattices made of synthetic strands and DNA thin films extracted from salmon (SDNA) with single-doping of Nd3+ or Er3+ and co-doping of Nd3+/Er3+ for high performance UV detection. The topological change of the DNA double-crossover (DX) lattices during the course of annealing was estimated from atomic force microscope (AFM) images to find the optimum concentration of Ln3+ ([Ln3+]O). No topological disturbance in DNA DX lattices were observed up to [Ln3+]O, and significant enhancement in the physical properties was obtained at [Ln3+]O. The interactions between Ln3+ and SDNA were examined using spectroscopic methods of UV-visible, Raman, and X-ray photoelectron spectroscopy (XPS). Current and photovoltage measurements for Ln3+-doped SDNA thin films under UV illumination with varying power intensities were conducted. Under UV illumination, the photocurrent and photovoltage of Ln3+-doped SDNA thin films increased with increasing applied external voltages and input power intensities, respectively. In addition, we observed considerable increases in photovoltage responses, i.e., 5-fold increase for Nd3+, 10-fold for Er3+, and 13-fold for Nd3+/ Er3+, compared to the pristine SDNA due to the additional charge carriers generated in Ln3+-doped SDNA thin films. Device performance was measured in terms of photovoltage responsivity and retention characteristics. These phenomena indicate the high stability and substantial endurance characteristics of Ln3+-doped SDNA thin films.

In gas sensors, metal oxide semiconductors have been considered as favorable resistive-type toxic gas sensing materials. However, the higher temperature operation of metal oxides becomes a barrier for their wide range of applications in explosive and flammable gas environments. In this regard, great efforts have been devoted to reducing the operating temperature of the sensor. We demonstrated a chemical resistor-type NO gas sensor based on p-i-n GaN nanorods (NRs) consisting of InGaN/GaN multi-quantum wells (MQW). The sensor exhibited superior NO gas sensing performance to p-type GaN NRs. Furthermore, it also showed a remarkably improved response and fast recovery under UV irradiation (λ = 367 nm) of different UV intensities (7 to 20 mw cm-2) under reverse bias. The sensing performance of MQW-embedded p-i-n GaN NRs was enhanced with the boosted response by 4-fold at 35 °C under UV irradiation. The significant decrease in the resistance of the sensor under UV irradiation was mainly due to the extraction of photo-generated carriers under reverse bias, which can enhance the ionization of oxygen molecules. In addition, the effect of relative humidity (30%-60%) on the gas sensing performance was also manifested in this study. The selectivity of the sensor was determined by using other gases (NO, NO2, O2, NH3, H2S, CO, and H2), which exhibited a low response towards all tested gases other than NO. The experimental results demonstrated that p-i-n GaN NRs with InGaN/GaN MQW is a promising material for the detection of NO gas. Specific emphasis was laid on the enhanced response of p-i-n GaN NRs in reverse bias under UV irradiation.

Although excellent milestones of III-nitrides in optoelectronic devices have been achieved, the focus on the optimization of their geometrical structure for multiple applications is very rare. To address this issue, we exclusively designed a prototype device to enhance the photoconversion efficiency and gas interaction capabilities of GaN nanorods (NRs) grown on a V-grooved Si(100) substrate with Si(111) facets for photodetector and gas sensor applications. Photoluminescence studies have demonstrated an increased surface-to-volume ratio and light trapping for GaN NRs grown on V-grooved Si(111). GaN NRs on V-grooved Si(100) with Si(111) facets exhibited high photodetection performance in terms of photoresponsivity (217 mA/cm

This chapter presents the GaN-based different devices for 5G applications. It includes the design and performance optimization of devices for the above mentioned application. The comparison between Si-based devices with GaN-based devices has been performed and The performance of GaN-based devices outplayed the Si-based devices.

The surface states, poor carrier life, and other native defects in GaN nanorods (NRs) limit their utilization in high-speed and large-gain ultraviolet (UV) photodetection applications. Making a hybrid structure is one of the finest strategies to overcome such impediments. In this work, a polypyrrole (Ppy)-poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)/GaN NRs hybrid structure is introduced for self-powered UV photodetection applications. This hybrid structure yields high photodetection performance, while pristine GaN NRs showed negligible photodetection properties. The ability of the photodetector is further boosted by functionalizing the hybrid structure with Ag nanowires (NWs). The Ag NWs-functionalized hybrid structure exhibited a responsivity of 3.1 × 103 (A/W), detectivity of 3.19 × 1014 Jones, and external quantum efficiency of 1.06 × 106 (%) under a UV illumination of λ = 382 nm. This high photoresponse is due to the huge photon absorption rising from the localized surface plasmonic effect of a Ag NWs network. Also, the Ag NWs significantly improved the rising and falling times, which were noted to be 0.20 and 0.21 s, respectively. The model band diagram was proposed with the assistance of X-ray photoelectron spectroscopy to explore the origin of the superior performance of the Ag NWs-decorated Ppy-PEDOT:PSS/GaN NRs photodetector. The proposed hybrid structure seems to be a promising candidate for the development of high-performance UV photodetectors.

Recently, III-nitride semiconductor nanostructures, especially InGaN/GaN quantum well nanorods (NRs), have been established as a promising material of choice for nanoscale optoelectronics and photoelectrochemical (PEC) water-splitting applications. Due to the large number of surface states, III-nitride NRs suffer from low quantum efficiency. Therefore, control of the surface states is necessary to improve device performance in real-time applications. In this work, we investigated the effect of hydrogen plasma treatment on the optical properties of InGaN/GaN single-quantum-well (SQW) NRs. The low-temperature photoluminescence (PL) studies revealed that yellow and green emissions overlapped and the yellow band is more dominant in the pristine InGaN/GaN SQW NRs. However, the emission corresponding to yellow luminescence was strongly suppressed and the green emission is more intensified in hydrogenated InGaN/GaN SQW NRs. Furthermore, the time-resolved PL spectroscopy studies revealed that the carrier lifetimes of hydrogenated InGaN/GaN SQW NRs are relatively short compared to the pristine InGaN/GaN SQW, indicating the effective reduction of non-radiative centers. From the PEC measurement, the photocurrent density of hydrogenated InGaN/GaN SQW NRs in the H2SO4 solution is found to be 5 mA cm-2 at -0.48 V versus reversible hydrogen electrode, which is 3.5-fold larger than that of pristine ones. These findings shed new light on the significance of surface treatment on the optical properties and thus nanostructured photoelectrodes for PEC applications.

In this work, for the first time, we have made InN/In

Although DNA (low-cost, highly transparent, low optical loss, biodegradable, non-toxic, and highly flexible) and gold nanoparticles (Au NPs, exhibiting interband transition and localized surface plasmon resonance) have been intensively studied, DNA with Au NPs in photodetectors is rarely discussed. Here, we constructed salmon DNA (SDNA) thin films and incorporated Au NPs to demonstrate efficient and high-performance UV photodetectors. The Au NP-embedded SDNA thin films were characterized with UV–vis absorption, Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and conductivity measurements in order to understand their physical and chemical properties. The FTIR and XPS measurements elucidated how Au NPs become embedded in SDNA, through analysis of chemical binding and chemical composition. A current increase was observed under UV illumination when performing conductivity measurements. In addition, photovoltage measurements were conducted to investigate the significance of photoresponse and retention characteristics. The density of d-band electrons in Au NPs and the charge carriers in SDNA were observed to increase under UV illumination, followed by a significantly enhanced UV photoresponse. From our observations, the photovoltage displayed a flat response over time, which indicated their stability, durability, and high Au NP retention.

In this work, reduced graphene oxide (rGO)/GaN nanorods (NRs) hybrid structure based sensors for hydrogen (H2) and hydrogen sulfide (H2S) gases has been demonstrated at room temperature. The morphological, elemental, and structural analyses were carried out by using scanning electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy. The electrical characterization of rGO/GaN NRs hybrid structures showed good rectifying behavior compared to pristine GaN NRs. The H2 and H2S gas sensing measurements at different gas concentrations revealed that the rGO/GaN NRs exhibit superior sensing properties compared to pristine GaN NRs. In order to find the gas sensing mechanism of rGO/GaN NRs, hybrid structure sensor is also tested with NOx gas. Our experimental results revealed that the rGO/GaN NRs are good candidates for selective detection of H2S gas. The rGO/GaN NRs showed remarkably improved response under ultra-violet (λ = 365 nm) illumination, the photogenerated carriers could be responsible for increasing response of the gas sensor at 30 °C under UV illumination. In addition, humidity test of the rGO/GaN NRs sensor was also conducted in this work. Our experimental results suggested that decorating GaN NRs with solution-processable rGO is one of the effective ways to enhance the response of GaN nanostructures.

Although the physicochemical properties of graphene oxide-Poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (GO-PEDOT:PSS) nanocomposite has widely reported, the urgency of this nanocomposite in the surface acoustic wave (SAW) technology still remains at the infancy stage. In this work, a high response SAW NO2 gas sensor was developed by depositing the GO-PEDOT:PSS nanocomposite on piezoelectric LGS substrate. The pristine LGS SAW sensor has showed a resonant center frequency of 136.10 MHz and it was shifted to 135.78 MHz for the GO-PEDOT:PSS coated LGS SAW sensor. The observed shift in resonance frequency likely due to the mass loading effect of GO-PEDOT:PSS nanocomposite interface. However, under the gas ambient the GO-PEDOT:PSS/LGS SAW sensor exhibited a significant negative differential frequency shift (Δf) of 5.89 kHz to100 ppm of NO2 gas with a good cycling stability, excellent sensitivity and a low detection limit (∼175 ppb) at room temperature (RT), while the pristine GO/LGS and PEDOT:PSS/LGS SAW sensors showed the Δf of about 0.9 kHz and 2.1 kHz, respectively. In addition, under the various relative humidity conditions at RT for 100 ppm of NO2, the GO-PEDOT:PSS/LGS SAW device showed a dominant Δf. Our experimental results divulged that the effect of mass loading is the responsible underlying mechanism for the superior NO2 gas sensing performances. In turn, the predominant mechanism between the chemical interface and NO2 gas molecules on GO-PEDOT:PSS/LGS SAW device has been deliberately discussed in detailed by comparing with chemo-resistive type gas sensing properties These intriguing results indicate that the significance of GO-PEDOT:PSS has a synergetic effect in SAW sensor applications.

Although gallium nitride (GaN) nanostructures are auspicious for photocatalytic activity, geometrical optimization has paid much attention for a significant light trapping in photoelectrochemical applications. To minimize the optical losses, we designed a prototype V-groove textured Si (100) with (111) facets, and GaN nanorods (NRs) were grown over a prototype substrate using plasma-assisted molecular beam epitaxy. The photocurrent density of V-groove textured GaN NRs in the NaOH electrolyte is found to be 801.62 μA/cm2 at 1.14 V vs reversible hydrogen electrode, which was 2.1-fold larger than that of GaN NRs on plain Si (111). Using this prototype V-groove textured Si(100) with (111) facets, a significant light can be trapped and modulated into GaN NRs. Furthermore, the heterostructure between GaN NRs and V-groove textured Si stimulates effective charge separation and transportation. These results represent an important forward step in solar photoelectrolysis.

In order to find the effect of hydrogen (H) treatment on leakage current and current conduction mechanism in GaN nanorods (NRs) Schottky diode, GaN NRs surface was subjected to H plasma treatment. Experimental results showed that Schottky barrier height (Φ b ) increased, while the ideality factor (n) decreases by the H treatment. The Φ b , n of as-grown GaN NRs were found to be 0.54 eV, 2.16, on the other hand in H treated GaN NRs Schottky diodes, Φ b was found to be increase to 0.72 eV, and n decreased to 1.30. Barrier inhomogeneity was confirmed by temperature dependence I-V parameters. The surface state density (N SS ) calculated from Terman's method were found to be 1.21 × 10 13 eV −1 cm −2 and 2.15 × 10 12 eV −1 cm −2 for as-grown and H treated GaN NRs respectively. These results suggested H treatment effectively passivate the surface states and decreased N SS could be leads to enhancement in the Schottky behavior of GaN NRs.

Understanding the metal/semiconductor interface is very significant for real-time optoelectronic device applications. In particular, the presence of interface states and other defects is detrimental to photodetector applications. In this study, the electrical transport properties of a pristine gallium nitride (GaN) nanorod (NR)-based Schottky diode are demonstrated at different temperatures by current–voltage characteristics in the range of 200–360 K. An enhancement in the Schottky barrier height (0.65 eV for hydrogen-passivated GaN NRs compared to 0.56 eV for pristine ones) is noticed. The effect of deep traps residing within the forbidden gap of GaN NRs is investigated using deep-level transient spectroscopy. Two deep defects are found at E C − 0.19 eV and E C − 0.31 eV in pristine GaN NRs; the E C − 0.31 eV defect peak is attributed to V Ga or nitrogen interstitials. After hydrogenation the peak at E C − 0.31 eV is suppressed and that at E C − 0.19 eV remains unchanged. The hydrogenated GaN NRs show a high photoresponse, which is nearly 2.83 times higher than that of pristine GaN NRs. The hydrogenated GaN NRs exhibit a photoresponsivity of 4.7 × 10−3 A W−1 and detectivity of 1.24 × 1010 Jones under UV illumination of λ = 382 nm. The enhanced performance is attributed to the deep defect passivation by hydrogenation along with the surface-state-free interface between the GaN NRs and metal contacts. The experimental results demonstrate the significance of hydrogen treatment use in the fabrication of GaN-based optoelectronic devices.

In this work, we demonstrated a single device of g-C3N4/GaN NRs heterostructure with dual functionality for self-powered ultraviolet light photodetector and selective NO2 gas sensor at room temperature. The g-C3N4/GaN NRs heterostructure demonstrated excellent photoresponse to UV illumination (λ = 392 nm) at zero bias with linear dependence on illumination power. Under 1.35 mW/cm−1 illumination power, the device exhibited high responsivity∼20 mA/W, and detectivity ∼5.16 × 1012 cmHz1/2/W. On the other hand, the g-C3N4/GaN NRs heterostructure exhibited remarkable response of 7.8 % for 5 ppm NO2 gas, while pristine GaN NRs showed negligible response. The potentiality of the gas sensor is further boosted by irritation of UV and visible lights, and the limit of the detection enriched to 500 ppb under UV illuminations at RT. UV light (P = 1.35 mW/cm2) greatly intensified the response by five-fold, and notably stimulated the recovery signal of the device for 500 ppb NO2. The increased response of heterostructure is ascribed to the sensitization of g-C3N4 and the adequate interface between g-C3N4 and GaN NRs that promoted the charge transport and separation effectively. The photodetector and NO2 gas sensing mechanism of g-C3N4/GaN NRs junction is discussed in detail by using energy band diagram.

Tungsten trioxide (WO3) is a promising material for ultra-violet (UV) photodetector applications. In this research, high sensitivity and external quantum efficiency (EQE) of UV photodetector test-device is fabricated by the deposition of WO3 films through sputtering at 10 mTorr sputter pressure. The effect of sputter pressure on the crystallinity and morphology as well as the photodetector performance of WO3 films is studied. Here, the thickness of the WO3 films is decreased from 225 nm to 95 nm as the sputter pressure is increased from 10 mTorr to 20 mTorr due to the low deposition rate upon accumulation of argon ions. The crystallinity and surface roughness are found to be high for WO3 film deposited at 10 mTorr as an effect of Ostwald ripening. The SiO2 layer on Si substrates acts as a passivation to inhibit the surface recombination and the ohmic-contact between WO3 and Ti electrode is helped to enhance the photocurrent. The higher crystallinity, tailored grain size, and surface roughness of WO3 films assist to achieve high responsivity and EQE by minimizing the overall impedance. Therefore, WO3 films deposited at 10 mTorr sputter pressure is suitable for UV photodetector applications with good stability and higher photodetector performance.

This paper reports the synthesis and characterization of ZnS:Gd nanoparticles prepared by a hydrothermal process using different doping concentrations. The chemical, structural, luminescence and magnetic properties of these nanoparticles were investigated by X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) spectroscopy, and vibrating sample magnetometer (VSM) measurements. XRD confirmed that all the samples had a cubic structure with good crystallinity. HRTEM showed that the particles were polycrystalline with a mean size of 4–6 nm. XPS revealed the oxidation state of Gd in the ZnS lattice to be +3. The PL spectra of all the nanoparticles exhibited broad emission peaks in the visible region. All the Gd doped nanoparticles exhibited well-defined ferromagnetic behavior at room temperature. The saturation magnetization increased significantly with increasing Gd concentration, reaching a maximum for 3 at.% Gd and decreasing for the 5 at.% Gd doped ZnS nanoparticles.

In this paper, we have investigated effect of Si doping and hydrogenation on room temperature ferromagnetism in GaN nanorods (NRs) grown on patterned Si (111) substrate by plasma assisted molecular beam epitaxy. Vibrating sample magnetometer measurements revealed that ferromagnetic properties enhanced with increased in Si concentration and maximum saturation of magnetization was about 0.023emu/g, which is three times higher than that of undoped GaN NRs. Hydrogenation of Si doped GaN NRs strongly suppresses the ferromagnetic behavior, while thermal annealing of hydrogenated GaN NRs revealed that recovery of ferromagnetic properties. Hydrogen compensates the free electron concentration in Si doped GaN NRs which tends to decrease ferromagnetic properties and recovery of ferromagnetic properties due to thermal dissociation of hydrogen atoms from GaN NRs. These results suggest that ferromagnetic properties enhanced in Si doped GaN NRs, which is possibly related to increase in free electron concentration.

Cr (0, 3 and 5 at.%) doped ZnS nanoparticles were successfully synthesized by hydrothermal method using PVP as capping agent. The influence of Chromium doping on the structural, luminescence and magnetic properties of ZnS nanoparticles is investigated. EDS spectra confirmed the presence of zinc, chromium and sulfur in the doped samples in near stoichiometric ratio. XRD and Raman analysis demonstrated successful incorporation of Cr3+ ions into ZnS lattice with the absence of metallic clusters or precipitates. TEM micrograph indicated that the particles were a few nm (

In this work, the first time we made InN/In2O3 core-shell heterostructure by hydrogen plasma treatment. InN nanorods (NRs) were grown by using plasma-assisted molecular beam epitaxy and hydrogen plasma treatment was performed by using the reactive ion etching system at room temperature. From X-ray photoemission spectroscopy studies, it was noticed that the bonding partner of In changes from N to O and N 1s completely disappeared in hydrogenated InN NRs. Further, high-resolution transmission electron microscopy revealed that the formation of InN/In2O3 core-shell NRs by hydrogenation plasma treatment. The resistance of pristine InN NRs was decreased in NO2 ambient. Interestingly, the resistance of the InN/In2O3 core-shell was increased while introducing NO2 gas. InN NRs surface exhibits downward band bending due to the electron accumulation, in NO2 ambient, the surface band bending was decreased due to the increase in bulk conduction channel. This reversed gas sensing behavior in InN/In2O3 core-shell NRs was attributed to the increase in depletion layer while reducing conduction channel width by absorption of NO2. The InN/In2O3 core-shell NRs exhibited a response of 22.43 % at 50 oC, which was 5.11 times higher than that of pristine InN NRs.